1. Field of the Invention
This invention relates generally to wireless and long distance carriers, Internet service providers (ISPs), and information content delivery services/providers and long distance carriers. More particularly, it relates to location services for the wireless industry, particularly for E-9-1-1.
2. Background of Related Art
When you dial 911, the call is directed to an assigned local Public Safety Access Point (PSAP). The PSAP picks up the call along with an inbound telephone number or Automatic Number Identification (ANI) information. This number is used to query an Automatic Location Identification (ALI) database, match it with the corresponding address as a location of the caller, and forward the location information and inbound telephone number to the assigned PSAP. The PSAP can then deliver both the number and the location to the appropriate emergency service (fire, police and ambulance) so that the emergency response unit can proceed to the appropriate location.
This above scenario works well when the 911 call originates from a residence, since every residential number is associated with a unique residential address. However, for wireless devices which are highly mobile, exact location information is critical in determining the correct PSAP to be used.
E911 is short for Enhanced 911, a location technology advanced by the FCC that will enable mobile, or cellular, phones to process 911 emergency calls and enable emergency services to locate the geographic position of the caller. When a person makes a 911 call using a traditional phone with ground wires, the call is routed to the nearest public safety answering point (PSAP) that then distributes the emergency call to the proper services. The PSAP receives the caller's phone number and the exact location of the phone from which the call was made. Prior to 1996, 911 callers using a mobile phone would have to access their service providers in order to get verification of subscription service before the call was routed to a PSAP. In 1996 the FCC ruled that a 911 call must go directly to the PSAP without receiving verification of service from a specific cellular service provider. The call must be handled by any available service carrier even if it is not the cellular phone customer's specific carrier. Under the FCC's rules, all mobile phones manufactured for sale in the United States after Feb. 13, 2000, that are capable of operating in an analog mode must include this special method for processing 911 calls.
The FCC has rolled out E911 in two phases. In 1998, Phase I required that mobile phone carriers identify the originating call's phone number and the location of the signal tower, or cell, accurate to within a mile. Phase I of the FCC's E911 rules requires that a 7, 8 or 10 digit number accompany each 911 call, which allows the PSAP dispatcher to either call back if the call is disconnected or to obtain additional information such as the mobile's callback number. It also gives the dispatcher the location at the cell site that received the call as a rough indication of the caller's location.
In 2001, Phase II required that each mobile phone company doing business in the United States must offer handset- or network-based location detection capability so that the caller's location is determined by the geographic location of the cellular phone within 100 meter accuracy—not merely to the location of the tower that is transmitting its signal. The FCC refers to this as Automatic Location Identification (ALI). Phase II of the FCC's wireless 911 rules allows the dispatcher to know more precisely where the caller is located.
Advances in technologies that employ new or upgraded handsets have demonstrated significant progress. However, as a practical matter, current FCC rules permit only network-based (i.e., independent of handset type) solutions to meet the Phase II requirements in the short term. As a result, the current rule effectively precludes use of a handset-based (i.e., GPS-assisted or other interaction dependent on the handset) approach, which needs to gradually replace or upgrade current handsets. Thus, in September 1999, the FCC revised its rules to permit the phase-in of new or upgraded handsets in order for handset-based solutions to be a viable competitor for initial ALI deployment under Phase II, while making other revisions aimed at promoting wireless E911 and improving public safety.
As can be appreciated, PSAP assigned regions do not correspond to cell site coverage areas. Many cell sectors' RF coverage crosses state and county borders between PSAPs, but a wireless carrier is only able to configure their wireless switches regardless of the number of PSAP regions covered (i.e., as in Phase I requirements) to route to only a single PSAP per cell sector.
Prior to Phase II implementation, it is possible that a small percentage of 911 dialers will be routed to an improper PSAP. This is because the call is routed based on the particular cell site that was used to communicate, rather than to the correct PSAP assigned to a caller's location. In such an instance, wireless E911 calls would require a transfer between PSAPs (usually performed manually by personnel at the incorrect PSAP) because the geographic location of the caller did not correspond to the first PSAP dispatcher's jurisdiction.
J-STD-036 provides a protocol for non-GSM wireless systems to select the correct PSAP based on the caller's precise location, and has the capability to greatly reduce the number of E911 calls that must be transferred between PSAPs (thus speeding up service). However, GSM systems do not have a similar solution for PSAP routing based on the caller's location only for routing based on the particular cell tower used by the caller.
Currently, in non-GSM systems, a selective router switch is used to select the correct PSAP based on receipt of an ISUP GenericDigitsParameter that contains emergency service routing digits (ESRD). An ESRD is a 10 digit routable, but not necessarily dialable number that is used for routing to a PSAP—but only on a per origination cell sector basis. Thus, the ESRD helps a selective router route a call to the particular PSAP assigned to the cell sector serving the 911 caller, causing the occasional need for manual or other type transfer of the PSAP caller.
A new ISUP CallingGeodeticLocation (CGL) parameter was defined in April 2000 to help a selective router select the appropriate PSAP based on the caller's precise location, not based only on the location of the serving cell tower, but this technology requires a software upgrade (e.g., to the ISDN User Part (ISUP) software) at many switches, thus deterring any emergence of this type solution. In fact, this particular technology may never appear since non-GSM wireless switches already utilize an existing protocol (J-STD-036) to determine PSAP selection prior to routing out of the wireless switch and it is only GSM wireless switches that would be served by this type of solution.
There is a need for an apparatus and technology to provide improved PSAP selection to reduce the need for transfers between PSAPs, and consequently to allow help to arrive for a wireless 911 caller that much sooner.